Manually-operable controlling device for electric motors.



C. REDFIELD. MANUALLY OPERABLE nonmoumc DEVICE FOR ELECTRIC MOTORS.

APPLICATION FILED AUG. 10. l9l6.

R 1 o 9. T 1 4 N Hm m w m w w r a; m fl w n m m a 0 .m m J m 7 C 3 6 J m w 0v 8 1. E s .4 m 1 W AITORNEY C. REDFIELD.

MANU'ALLY OFERABLE CONTROLLING DEVICE FOR ELECTRIC MOTORS.

APPLICATION FILED AUG. 10. I916.

1,296,698. Patented Mar. 11,1919

4 SHEETS-SHEET 2.

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i 67 l 57.16 .9 1 3127 I a y O I I Clevelandjietififilti; 56 6L6- INVENTOR, WITNESSES ATTORNEY c. .REDFIELD. MANUALLY OPERABLE CONTROLLING. DEVICE FOR ELECTRIC MOTORS.

APPLICATION FILED AUG. i0. I916.

Patentd Mar. 11,1919.

4 SHEETSSHEIZT 3.

WITNESSES Al I ORNEY C. REDHELD.

MANUALLY OPERABLE CONTROLLING DEVICE FOR ELECTRIC MOTORS.

' APPLICATION EILED AUG-l0. I9I6. 1,296,698

Patented Mar. 11,1919.

4 SHEETS-SHEET 4.

INVENTOR,

WITNESSES UNITED STATES PATENT OFFICE.

CLEVELAND REDFIELD, 0F OGDEN, UTAH, ASSIGNOR TO AUTOMATIC CONTROLLER AN D MANUFACTURING COMPANY. 'A CORPORATION OF UTAH.

MANUALLY-OPERABLE CONTROLLING DEVICE FOR ELECTRIC MOTORS.

Specification of Letters Patent.

Patented Mar. 11, 1919.

Application filed August 10, 1916. Serial No. 114,239.

To all whom it may concern:

Be it known that I, CLEVELAND REDFIELD, a citizen of the United States, residing at Ogden, in the county of Veber and State of Utah, have invented a new and useful Manually-Operable Controlling Device for Electrio Motors, of which the following is a specification.

This invention has reference to controlling devices for electric motors, and its objectis to provide a manually operable controlling device of simple form and so arranged that it is of greatly simplified construction over other controlling devices in common use, but rendering a service superior to such other controlling devices, and in which the maintenance requirements are greatly reduced.

The present invention comprises essentially compensatin or inductance coils employed in connection with a magnetic cirtents, the opening or gap widening slowly at first and then with progressively increasing rapidity. In this manner the magnetic reluctance provided in the motor circuit may be large at the beginning and then decrease approximately similar to the electrical demand of the motor in starting and attaining speed so that the decrease in inductance may be made approximately proportional to the decrease in the demand ofthe motor. In accordance with the invention the parts are manually actuated or operated and provision is made, by the introduction of a prolonged time element in the operation, to constrain the operator to sensibly constant actuation.

The controlling device and its manner of operation is such that the motor may be the operation of the device is local to the device itself, and ismanually performed instead of being electromagnetically performed as in the companion case. Moreover, those parts of the invention which are common to both applications are claimed in the companion case, wherefore no claims to such common subject-matter which could properly be made in the companion case are herein made.

The invention will be best understood from a consideration of the following de tailed description, taken in connection with the accompanying drawings forming part of this specification, with the further understanding that while the drawings show a practical form of the invention, the latter is not confined to any strict conformity with the showing of the drawings, but may be changed and modified so long as such changes and modifications come within the scope of the appended claims.

In the drawings:

Figure 1 is an elevation with some parts in section of a controller box embodying the present invention, the box itself being in longitudinal section and the parts being shown in the inoperative position, that is, with the motor standing still and the controller box ready for actuation to start the motor.

Fig. 2 isa View similar to Fig. 1 except that the view is taken from the right hand side of Fig. 1.

Fig. 3 is a view similar to Fig. 1 but omitting some of the parts and showing the position of the controlling mechanism in the full-speed running position of the motor.

Fig. 4 is a section on the line 4-4 of Fig. 1.

Fig. 5 is a wiring diagram of the circuit connections for the mechanism withinv the controller box and also showing the line and motor connections.

Fig. 6 is a similar diagram for a variable speed motor.

Fig. 7 is a fragmentary section of a manipulating device which may be substituted for that shown in the other figures.

Fig. 8 is a .plan view of a portion ofthe structure shown in Fig.7. Fig. 9 is a view similar to but less com-- prehensive than Fig. 1, showing the application of the structure of Fig. 7.

Referring to the drawings there is shown 'the free ends of the legs or cores 7.

a controller box composed of a casting 1 following the general outline of the box and having legs 2 and 2 extending lengthwise of the box. In the installed position of the controller box the casting 1 is at the upper end of the box, since the box is customarily installed in the. upright position, and the legs 2 and 2 depend therefrom and extend toward the bottom of'the box, terminating near said bottom. -,The casting 1 Carries by means of screws .3 a casing 4 which may be conveniently made of sheet and breaking devices or switches located in what may be termed the lower portion of the casing. 4.

Within the controller box between, the legs 2'and supported by rods 5 extending between the legs 2 is a magnetic yoke 6 having legs 7 projecting therefrom, the yoke being laminated, as is customary in alternating current apparatus. In the particular showing of the drawings the yoke 6 is upright and the legs 7 extend therefrom in a direction perpendicular to the length of the yoke and in equi-distantly spaced relation. Mounted on each leg 7 is a coil 8, the coils being designed to operate as inductance or-compensating coils for a purpose which will be hereinafter described. The legs 7 constitute cores for the coils 8, while the main body of the yoke 6 constitutes a fixed magnetic bridge or yoke for the cores 7. There is also provided a bar 9 which, like the fixed magnetic member 6, is laminated, and this bar 9 constitutes a magnetic bridge for the other ends of the cores 7, being long enough for the purpose and, moreover, being movable with relation to When thebar is in bridging engagement with the free ends of the cores 7 there is produced a closed magnetic circuit for the coils 8, but the extent of movement of the bar 9 away from the cores 7 is sufiicient to provide an air gap so largethat the magnetic linesof force no longer find a path through the bar 9. In stating that the'bar 9 is in engagement with the free ends of the cores 7, it is to be understood that such expression does not preclude the employment of any of the usual anti-sticking expedients by which freezing of magnetic surfaces together is prevented. I

In the structure of the present invention the movement of the bar 9 with respect to the cores 7 is the same for each, wherefore the bar 9 has a parallel motion mounting. This is brought about by carrying the bar 9 nearer the ends upon links 10 and 11, respectively, the links being each pivoted at one end to the bar and at the other end to some fixed portion of the device, as, for instance, upon rods 12, 13, respectively, secured at their ends in the respective legs 2*. The arrangement is such that when the bar 9 is against the legs 7 the links 10 and 11 are about horizontal in the installed position of the device. By moving the bar 9 up wardly it follows a curved path having longitudinal center lines of the pins 12 and 13 as axes, wherefore the bar moves away from each leg 7 equal with respect to the other legs. Moreover, if the movement of the bar away from the legs be regular, an

air gap is produced which with respect to the time of movement, which is regular, increases slowly jat first and then progressively more rapidly. The air gap in time of movement and increase of extent or length may correspond very closely to the demand of an alternating current motor in starting from rest and attaining speed. In the particular showing of the drawings the controller is assumed to be designed for a polyphase motor, and specifically a three phase motor, wherefore there are three coils 8. If a two phase motor were used two coils would be sufficient, and so on, the number of compensating or inductance coils agreeing with the number of phases in the feeding circuit.

Mounted on the rod 13 are rockers 14, 15, respectively, these rockers being in the main alike and each having arms 16, 17, respectively, on opposite sides of the rod 13. The arm 16 of the rocker 14 is widened at the outer end and one corner is formed with a tooth 18 adapted to engage behind a nose 19 on one end 20 of a gravity latch member 21, Which in turn is carried by a stud 22 fast to .one of the legs 2 at an appropriate point thereon. The latch 21 has another leg 23 on the side of the stud 22 remote from the leg 20, which latter is made of sufficient bulk to overbalance the leg 23, wherefore the latch member becomes a gravity latch, which would yield to the passage of the arm 16 of the rocker 14 until ultimately the nose 19 will drop in front of the tooth 18 and hold the rocker member from return movement. The other arm 17 of each rocker 14 and 15 is formed with an elongated slot 24 suitably shaped for a purpose which will presently appear.

livoted to the arms 16 of the rockers 14 and 15 are links 25, one for each rocker, and these links in the normal position of the parts are pendent. being joined at the upper ends by a pin 26. The links 25 are longer than the distance between the links 10 and 11 and are spaced from the respectii'e rockers 14 and 15 by lug 27 which may be formed on the respective arms 16 and carry studs 28 by means of which'the links 25 are pivoted to the respective rockers 14 and 15.

In the position of the arts prior to starting the'motor, the lugs 27 are dropped below the links 11, so that these lugs must be lifted for a distance before engaging the links 11. Then, however, engagement takes place, the lugs 27 tend to move the links 11 about the rod or pin 13 upon which they are mounted and so lift the bar 9 through a curved path due to the connection of the bar by the links 10 and 11 to a fixed part of the box.

A normal constraint or bias toward the inactive position of the parts is imparted to the rockers 14 and 15 by a spring 29 connected at one end to the arm 17 of the rocker 15 and at the other end turned about the pin or rod 12. But one spring 29 is needed since the two rockers are connected together through the links 25 and the pin 26.

Secured to the pin 26 about midway of its length is an eye 30 on one end of a screwthreaded stem 31 on which the screw threads are of relatively steep pitch. The screw stem 31 enters a longitudinally extended nut 32 mounted on and upstanding from a cap plate 33 secured to the casting 1 by screws 34 or otherwise and constituting a removable closure for the box, whereby access may be readily had to the interior of the box' when desired, without the necessity of removing the casing 4. The cap plate or cover 33 is formed with a boss 35 rising above the top of said cap plate and traversed by the stem 31. That face of the cap plate constituting its under face in the installed position has a countersink 36 immediately beneath and entering the boss 35. The nut 32 has an exterior intermediately located flange 37 having its circumferential continuity broken by a gap 38, one end wall 39 of which is undercut to'provide a beveled end wall for a purpose to be described. The nut 32 is designed to'turn about its longitudinal axis without longitudinal movement in order to impart longitudinal movement to the screw stemjl. Because of this the flange 37 is supported upon anti-friction devices .40 carried in a race-way in the boss 35, and that end of the nut constituting the lower end is continued into the countersink 36 and there exteriorly threaded and carrying a nut 41, thus holding the nut to the cap plate without interference with the rotation of the nut.

Applied to the nut above the flange 37 is an axially elongated hub 42 carrying near one end a crank arm 43 terminating at the end remote from the hub in a handle 44. The hub 42 has one end 45 closed and is long enough to provide between the upper end of the nut 32 and the end 45 of the hub 'a chamber inclosing a spring 46 tending to lift the hub 42 with respect to the nut 32. Limited longitudinal movement of the hub form a bevel tooth 49 adapted to enter the cut-away portion 38 of the flange 37 and engage the beveled end wall 39 thereof.

In the ordinary condition of the parts the 4 spring 46 holds the hub 42 and crank arm 43 raised, but the spring will-yield to properly applied pressure, so that the crank arm 1 may be depressed, whereupon the-tooth 49 will enter the recess 38 and then by a turning movement of the crank arm is brought into engagement with the beveled end wall 39, whereupon further rotative movement of the crank arm is participated in by the nut 32 with the result that the rotating nut draws the threaded stem 31 into it to such extent as the number of turns imparted to the nut may cause.

The pitch of the threads on the screw stem and in the nut receiving it may be relatively'steep, so as to reduce the necessary number of turns of the manipulating handle, but which will cause a sufficient number of turns, so that thecontroller mechanism may not be actuated too quickly. The amount of longitudinal movement of the screw stem 31 is such that the rockers 14 and 15 are moved aboutitheir pivotal axis represented by the pin 13 to an extent which will bring the tooth 18 behind the nose-19 and will move the bar 9 so far away from the free extremities of the legs 7 that practically all the magnetic lines of force will pass from leg to leg, of the fixed part of the magnetic structure, carrying the "coils 8, while the movable part represented by the Rafa 9 is practically out of the magnetic The free end of the arm'23 of the gravity pawl 21 is in the path of an upright rod 50 passed at its lower end through a guide lug 51 projecting from one of the legs 2 The rod 50 is ofa length to extend through the cap plate 33 and is there providedwith a head 52 serving as a manipulating head, and also as a stop head by which the rod is prevented .from dropping beyond a certain extent. The rod 50 extends through a solenoid 53 and in operative relation to this solenoid the rod carries a core-54 movable on the rodbetween two stop collars 55, 56

thereinto and striking the collar 56 raises the rod 50 sufficiently to permit the gravity pawl 21 to move so that its nose 19 is in the path of the arm 16 of the rocker 14 to drop into the path of the tooth 18 when the arm 16 of the rocker is raised. The solenoid 53 is designed to operate as a no-voltage solenoid, holding the rod 50 in elevated inactive position so long as the controlled motor is in operation and there is current upon the line, or in the motor leads. When the coil 53 is de'e'nergized the core 54'immediately drops along the rod 50 and striking the collar 55 propels the rod against the arm 23 of the gravity pawl 21, thereby releasing the rocker 14, assuming that the parts have been actuated in a manner to be described so that the controlled motor is running. The weight of the parts sustained by the screw stem 31 together with the biasing tension of the spring 29 will cause the screw stem 31 to rotate the nut 32 and the screw will drop in a direction of its length because of the weight imposed upon it, and, therefore, the bar 9 previously moved away from the magnetic structure represented by the yoke 6 and legs 7 is moved into bridging relation to the legs 7. These movements are under the assumption that after the crank arm 43 has been turned in a manner to draw the screw into the nut 32, the crank arm hasbeen released and the action of the spring 46 thereupon raises the crank arm so that the tooth 49 is no longer in engagement with the beveled wall 39, but out of the path of vthe latter.

. Within the controller box there are overload solenoids 57 carried by a plate 58 in turn carried by the pins 12 and 13, the plate 58 also carrying a solenoid 53. The plate 58 carries a bracket 59 which in turn carries a rod 61 on which are fixedly mounted gravity blocks each overriding a respective solenoid 57 and one of which is provided with an arm 60 to which is pivoted one end of a rod 62 extending through the guide lug 51 into position to engage the arm 23 of the gravity pawl 21. Each solenoid 57 is provided with a core 63 so arranged that when drawn into the respective solenoid it will engage the respective gravity block 60 rocking it in a manner to move the rod 62 into engagement with the gravity pawl 21, and thus release the rocker 14 if then held by the gravity pawl. In order that the movements of the cores 63 may be made sufliciently sluggish, each core 63 has a dash pot 64- associated therewith. I

Pendently supported by the legs 2 are links 65 pivoted by cars 66 to like ends of rods 67, the other ends of which rods enter respective sleeves 68 mounted to rock on studs 69 projecting from the lower ends of ilu' logs The sleeves 68 form part of a F supporting structure for an insulating strip 70 carrying contact terminals 71, 72 in position to be engaged by other contact terminals 73, 74 upon an insulating strip 75 carried by the bars 67.

The slots 24 are traversed by a rod 76 connecting the links 65 and the slot is so shaped that as the rockers 14 and 15 move, the links 65 are rocked in a manner to bring the contacts 73 and 74 into engagement with the contacts 71 and 72, but the contacts 74 being longer than the contacts 73 make engagement with the contact 72 before the contacts 71 and 73 arebrought together.

The cover member 33 also carries a reversing switch structure 77, which being of ordinary construction needs no special description. The reversing switch 77 is controlled by a turn button 78 on the exposed face of the cover member 33, so as to be always readily accessible.

The manipulating device shown in Figs. 7 and 8 is in most part similar to the like manipulating device shown in the other fig ures of drawing, but differs in some respects therefrom. The cap plate 33 has a boss 35 with a countersunk portion 36 as before. There is also provided a nut 32 corresponding to the nut 32 ,of the structure of Fig. 1, the nut 32 having a circumferential flange 37 and is also provided with a holding nut 41 entering the boss 35 all in like manner to the structure of Fig. 1. The boss 35 is, however, surrounded by a ring. 79 shown separately in Fig. 8. This ring is held in place by screws 80 and on the surface remote from the plate 33 has a circular series of notches or depressions 81.

There is also provided a crank arm 82 similar to the crank 'arm 43 and having a manipulating handle 83 axially traversed by a push rod 84 terminating above the handle in a manipulating head 85. Carried by the crank arm beneath the latter is a lever 86 pivoted to the crank arm by a pin 87 traversing cars 88 on the crank arm. The lever 86 is engaged at one end by a push rod 84 and at the other end has a tooth 89 adapted to enter a recess 90 in the flange 37, so that the crank arm may engage the nut or by an appropriate manipulation of the rod 84 may be released therefrom. The lever 86is maintained in normal engagement in the recess 90 by means of a spring 91 lodged in an enlargement 92 ofthe crank arm 82 and held in place by a set screw 93. The crank arm 82 is provided with a hub 94 generally similar to the hub 42 of Fig. 1. The hub 94 is held to the nut 32 by a set screw 95 entering a circumferential groove 96 in the nut 32 similarly to the arrangement of Fig. 1, but the set screw 95 while permitting turning movements of the nut and hub independently of each other, if desired, does not permit longitudinal movements of the hub on the nut. The hub is pin 101, however,.is so arranged that while temporarily holding the crank arm in different positions, will not resist a purposely applied force tending to further rotate the crank arm in either direction.

In the manipulating structure of Figs. 7, 8 and 9, the rockers 14 and 15 are controlled as before but the gravity detent or latch pawl 21 is omitted, as well as those parts which depend upon the full speed position of the controller. The controlling means for the magnetic circuit so far as the arrangement of Figs. 7 and 8 is concerned, is shown in Fig. 9.

With the structure of Figs. 7, 8 and 9 the controlling devices may be set in numerous positions, whereby correspondingly different speeds of the motor are possible. With the structure of either Fig. lor Fig. 7 it may be assumed that it is necessary to rotate the crank four times in order to move the parts from rest to full speed position. Under such circumstances the structure of Fig. 7 permits twenty-four positions in all. These particular figures are, however, to be taken as mere illustrations of any arrangement which may be found desirable to meet difi'er ent conditions. In the structure of Fig. 1 the controller is moved from position of rest progressively to the full speed position. In the structure of Fig. 7 the controller may be moved from a position of rest to that of full speed or various intermediate speeds and may be moved forwardly or backwardly to change the speed of the motor as may be found desirable. v

The controller ma be employed under any conditions for w ich it may be useful, and in Figs. 5 and 6 there are shown wiring diagrams of the controller connected to a constant speed motor 103 in the diagram of Fig. 5 and to a variable speed motor 104 in the diagram of Fig. 6. This showing is deemed to be a suflicient indication that the controller may be connected up in various ways to different apparatus without the necessity of further showing. In Fig. 5

main line conductors 105 are shown, and

these may be considered as the conductors of a three-phase system. One of the coils 8 of the controller is connected at one end to one of the main line conductors by a branch conductor 106, while the other end ofthe coil is connectedby a conductor 107 to one of the switch contacts, say, the contact- 72. Branched around the coil 8 is another conductor 108 co nected to another contact of the switch, say, the contact 71, and including one of the overload coils 57. Another one of the coils 8 is connected on one side by a conductor 109 to one terminal of the pole changing or reversing switch 77 and another terminal of this pole changer is connected by a conductor 110 to another one of the mains 105. The third main 105 is connected by a conductor 111 to another terminal of the pole changer 77 and the latter is connected by a conductor 112 to one end of the third one of the coils 8. The last I two named coils 8 are connected as the firstnamed coil 8 to respective switch contacts 72 and the second one of the over-load coils 57 is branched about one of the secondnamed coils 8 and is connected to a corresponding switch contact 71, while the remaining one of the coils 8 is shunted by a conductor 113 connected to the remaining one of the contacts 71 of the switch.

Each set of conductors 73 and 74 of the switch is connected to respective leads 114 in turn connected to the field winding of the motor 103. The no-voltage coil 53 is branched by conductors 115 across the motor 103, so that when the motor is running the coil 53 is energized and the bar 50 is held away from the latch 21. The diagram of Fig. 5 illustrates the circuit connections for a structure such as shown in Fig. 1, while the diagram of Fig. 6 illustrates the circuit connections which may be employed in connection with the structure of Figs. 7, 8 and 9.; In Fig. 6 the corresponding ends of the coils 8. are coupled together in multiple by a conductor 116, while the opposite ends of the coils 8 are connected by respective conductors 117 to respective leads 118 of the armature of the motor 104 diagrammatically these windings are connected by respective conductors 123 to contact terminals 124 of a switch having contact terminals 125 connected by conductors 126 to the main 105 of a threephase circuit, certain of the conductors 126 including a reversing switch 77.

The contacts 121 and 124 correspond to the contacts 73 and 74 and the contacts 120 and 125 correspond to the contacts 71 and 72 of the switch structure shown in Figs. 1, 2, 3 and 4, but omitted from Fig. 9, although assumed to be there present and also indicated in Fig. 5. 1 i

In the arrangement of Fig. 6 it is assumed that the reversing switch 77 is first properly set in accordance with the desired direction of rotation of the motor, and then the cir-f netic circuit of the coils 8 is broken in a manner already described with reference to the structure of Fig. 1 to first produce a small and gradually increasing air gap with the air gap progressingly accelerating, assuming that the motor is to be brought up to full speed, until the magnetic circuit is fully broken between the bar 9 and the legs 7 of the yoke 6, at which time the contacts 121 close on the contacts 120, thus short circuiting the armature 119 However, the structure of Figs. 7, 8 and 9 may be so manipulated as to arrest the movement of the bar 9 away from the legs 7 so that the air gap may bemade of any desired extent within the limits of the apparatus, thus causing the motor to run at speeds corresponding to the size of the air gap, so that the motor 104 may be. run at any speed desired within the limits provided for by the apparatus. Let it be assumed that the structure of Figs. 7, 8 and 9 is in position ready for starting, that is, with the bar 9 in engagement with the extremities of the legs 7 and either actually or effectively closing the magnetic circuit. If in this position of the parts the crank handle 82 is not at the time locked with the nut 32, the crank handle is turned sufliciently so that the tooth 89 is brought into coincidence with and drops into the notch 90 in the flange 37, thus locking the crank handle and nut together. Now by a suitable manipulation of the crank handle it is turned in a direction to draw the threaded stem 31 into the nut, this movement being in efiect a step by step movement due to a temporary arrest of the rotation of the crank handle, because of the dropping of the pin 101 into successive recesses 81 of the ring 79, but the arrangement is such that the stoppage need not be actual, but simply the positions are made sensible to the operator. At the same time the holding power of the pin 101 when lodged in a notch 81 is suflicient to prevent accidental rotation of the crank handle 82, thus holding the parts in the position to which they are brought by rotation of the crank handle, but not interfering with further movement of the crank handle in either direction at the will of the operator. The operator may by rotating the crank 82 move the bar 9 away from the legs 7 to varying extents, temporarily locking the parts in any one of numerous positions in accordance with the number of recesses 81 and the pitch of the screw '31. When it is desired to release the crank arm 82 from its engagement with the nut 32 the lever 86 is rocked by pushing upon the head 85 and then the parts may be returned to the first or cut-out position because the nut 32 is then free to rotate and the screw 31 because of its long pitch may be read y w thdra n from the nut until the bar 9 is again seated against the legs 7 and the magnetic circuit of 'first widening slowly and then with progressively increasing rapidity at substantially constant speed of operation of the manual means, said manually operable means including means for introducing into its operation a prolonged time element, whereby a variation of the magnetic gap may be made to approximately correspond to the demand of the motor in starting and attaining speed or vice versa.

2. In a controlling device for alternating current electric motors, inductance means for controlling the flow of current to the motor, and means whereby the magnetic reluctance of the magnetic circult of the inductance means may be varied at a rate and to an extent corresponding tothe demand of the motor for voltage in starting and attaining speed, said second named means including manually operable means for actuating the second named means and having a range of travel to introduce a prolonged time element into the operation. 2

3. In a controlling device for alternating current electric motors, inductance means for controlling the flow of current to the motor, means for causing increasing or decreasing magnetic reluctance 1n the mag-.

netic circuit of the inductance means at a progressively accelerating rate or vice versa, said second named means including manually operable means for moving it and having a range of travel for causing the action of the manually operable means to occupy a period of time which may correspond to the time occupied by the motor in starting and attaining speed under load conditions.

4. In controlling means for alternating current electric motors, inductance means for controlling the flow of current to the motor and provided with an initially closed magnetic circuit, and means for opening the magnetic circuit in a manner corresponding approximately to the electrical demand of the motor in starting and attaining speed, said second named means including manually operable means having an extent of travel to prolong the opening movement of the magnetic circuit through the desired time period.

5. In a controlling device for alternating current electric motors, inductance means for controlling the flow of current to the motor and having an initially closed magnetio circult, andumeans for opening the magnetic circuit and capable of actuation at a rate and to an extent which may approximate the demand of the motor for voltage in starting and in changing speed, said opening means including a screw member, a nut member therefor, and means for causing relative movement between the nut and the screw with the pitch of the latter proportioned to require a plurality of full turns to effect the travel of the nut and screw with relation to each other in opening the magnetic circuit to the full extent .provided.

6. In a controlling device for alternating current electric motors, inductance means for controlling the flow of current to the motor and having an initially closed magnetic circuit, and means for opening the magnetic circuit and capable of actuation at .a rate and to an extent which may approximate the demand of the motor for voltage in starting and in changing speed, said means including a threaded stem, a rotatable nut on the stem held against movement in the direction of the length of the stem, and means adapted to be grasped by the hand of an operator and engaged with the nut for turning the latter.

7. In a controlling device for alternating current electric motors, inductance means for controlling the flow of current to the motor and provided with an initially closed magnetic circuit, and means for opening the magnetic circuit and capable of actuation at a rate and to an extent which may approximate the demand of the motor for voltage in starting and in changing speed, said opening means including a screw, a rotatable nut on the screw held against movement in the direction of the length of the screw, and means adapted to be grasped by the hand of an operator and engaging the nut for turning the latter, the parts controlled by the screw and nut having a normal tendency to return to the first position and the pitch of the threads of the screw and nut being such as to permit the withdrawal of the'screw from the nut when the parts are released to return to the first position.

8. In a controlling device for alternating current electric motors, inductancemeans for controlling theflow of current to the motor and provided with an initially closed magnetic circuit, and means for opening the magnetic circuit and capable of actuation at a rate and to an extent which may approximate the demand of the motor for voltage in starting and in changing speed, said second named means having a normal constraint toward the initial position and including manually operable means for opening the magnetic circuit with said manually operable means having a range of movement to prolong the time of opening the magnetlc circult under normal condltions to the do sired extent and also having means for auton'iati'cally holding the parts against return movement to the initial position.

9; In a controlling device for alternating current electric motors, inductance means for controlling the flow of current to the motor and provided with an initially closed 1 magnetic circuit havingmeans for producing a gap therein, said gap-producing means including means whereby the gap may be widened at a rate and to an extent which may approximate the demand of the motor for voltage in starting and attaining speed,.

means for imparting to the gap-producing means a normal constraint toward the closed position, and means for the manual operation ofthe gap-producing means comprising a screw-threaded stem connected thereto and having threads of long pitch, a rotatable nut receiving the threaded stem and held against movement lengthwise of the latter, and actuating means for the nut adapted to be grasped by the hand of an operator to engage and turn the nut and provided with means whereby it may be secured to orreleased from the nut at will.

10. In a controlling device for alternating current electric motors, inductance means for controlling the flow of current to the motor and provided'with an initially closed magnetic circuit having means for producing a gap therein, said gap-producing means including means whereby the gap may be widened at a rate and to an extent which may approximate the demand of the motor for voltage in starting and attaining speed,

means for imparting to the gap produc-.

prising a screw -threaded stem connected thereto and having threads of long pitch, a rotatable nut receiving the threaded stem and held against movement lengthwise of the latter, and actuating means for the nut adapted to be grasped by the hand of an operator to engage and turn the nut and provided with means whereby it may be secured to or released from the nut at will, the pitch of the threads of the screw being such as to require a plurality of turns of the nut to effeet the full travel of the screw, whereby the time of normal operation of the gapproducing means is prolonged to the extent necessary to make the Widening of the gap I approximately proportional to the demand of the motor in starting and attaining speed. 11. A controlling device for alternating electric currents having electromagnetic means with movable means for varying the magnetlc reluctance thereof, and means -for actuating the movable means for varyingcoupling the manually operable member at will to the part to be actuated thereby.

12. A controlling device for alternating electric currents having electromagnetic means with movable means for varying the magnetic reluctance thereof, and means for actuating the movable means for varying the magnetic reluctance comprising a long pitch screw, a nut engaging the screw, means for rotating the nut consisting of a crank handle, and temporary locking means between the crank handle and the nut.

13. A controlling device for alternating electric currents having electromagnetic means with movable means for varying the magnetic reluctance thereof, and means for actuating the movable means for varying the magnetic reluctance comprising a screw threaded stem, arotatable nut engagin the stem, a crank handle with means for holding it to and releasing it from the nut, and automatically operable means for locking the nut temporarily in different positions of rotative adjustment.

14. A controlling device for alternating electric currents having electromagnetic means with movable means for varying the magnetic reluctance thereof, and means for actuating the movable means for varying the magnetic reluctance comprising a screw threaded stem, a rotatable nut engaging the stem, a crank handle with means for holding it to and releasing it from the nut, and automatically operable means for locking the nut temporarily in difierent positions of rota- 5 tive adjustment, said last-named means comprising a member in fixed relation to the controller and having a series of notches therein, and an elastically yieldable member on the nut temporarily engageable in any 4 one-of the notches.

15. A controlling device for alternating electric currents, having electromagnetic means with movable means for varying the magnetic reluctance thereof, and means for actuating the movable means for varying the magnetic reluctance comprising a screw threaded stem, a rotatable nut engaging the stem, a crank handle slidable on the nut in the direction of the length of its axis, with 5 the nut and crank handle having coacting parts for temporarily locking them together, and elastic means having a normal tendency to release the crank handle from the nut.

In testimony that I claim the foregoing as my own I have hereto aflixed my signature in the presence of two witnesses.

MARIE L. LEWIs, JOHN H. SIGGERs. 

